1. Technical Field of the Invention
The present invention relates to photoprotective compositions comprising at least one aqueous phase and a system for screening out UV radiation, which comprise:
(a) at least one partially or totally neutralized, crosslinked or non-crosslinked amphiphilic polymer of 2-acrylamidomethylpropanesulfonic acid, and
(b) at least one water-soluble silicone comprising at least one terminal or pendent monovalent polyoxyalkylene group.
This invention also relates to a combination of at least one partially or totally neutralized, crosslinked or non-crosslinked amphiphilic polymer of 2-acrylamidomethylpropanesulfonic acid and of at least one water-soluble silicone comprising at least one terminal or pendent monovalent polyoxyalkylene group, in an aqueous cosmetic composition comprising a photoprotective system capable of screening out UV radiation, to increase the sun protection factor.
2. Description of Background and/or Related and/or Prior Art
It is well known that light radiation with wavelengths of between 280 nm and 400 nm permits tanning of the human epidermis and that rays with wavelengths of between 280 nm and 320 nm, which are known as UV-B rays, cause skin burns and erythema that can harm the development of a natural tan; this UV-B radiation should thus be screened out.
It is also known that UV-A rays, with wavelengths of between 320 nm and 400 nm, which cause tanning of the skin, are liable to induce an impairment in the skin, especially in the case of sensitive skin or skin that is continually exposed to solar radiation. UV-A rays in particular bring about a loss of elasticity of the skin and the appearance of wrinkles, leading to premature aging. They promote the triggering of the erythmal reaction or amplify this reaction in certain individuals and may even be the cause of phototoxic or photoallergic reactions. It is thus desirable also to screen out UV-A radiation.
UV-A and UV-B rays should thus be screened out, and cosmetic compositions for protecting the human epidermis containing UV-A and UV-B-screening agents currently exist.
These antisun compositions are quite often in the form of an emulsion, of oil-in-water type (i.e., a cosmetically and/or dermatologically acceptable support consisting of an aqueous dispersing continuous phase and of a fatty dispersed discontinuous phase), or of water-in-oil type (aqueous phase dispersed in a continuous fatty phase), which contains, in varying concentrations, one or more standard liposoluble organic screening agents and/or standard water-soluble organic screening agents capable of selectively absorbing the harmful UV radiation, these screening agents (and the amounts thereof) being selected as a function of the desired sun protection factor, the sun protection factor (SPF) being expressed mathematically as the ratio of the dose of UV radiation required to reach the erythema-forming threshold with the UV-screening agent to the dose of the UV radiation required to reach the erythema-forming threshold without the UV-screening agent. In such emulsions, the hydrophilic screening agents are present in the aqueous phase and the lipophilic screening agents are present in the fatty phase.